Scientists investigate the possibility of human cannabinoid exposure from meat consumption if cattle are fed hempseed cake.

Researchers from North Dakota State University (NDSU) and the USDA’s Agricultural Research Service (ARS) recently discovered that cattle-fed hempseed cake, an industrial hemp byproduct, retained very low levels of cannabis chemicals (cannabinoids) in muscle, liver, kidney, and fat tissues.

Because the amount of cannabinoid residues (Cannabidiol [CBD] and Tetrahydrocannabinol [THC]) remaining in edible animal tissues has not been characterized, hempseed cake cannot be used in food animal rations at this time.

A team of USDA-ARS and NDSU researchers, led by Research Physiologist David J. Smith, looked at cannabinoid residues (CBD and THC) in edible tissues of cattle-fed hempseed cake to see if it could be used safely as a source of protein and fiber in cattle feed. Scientists discovered that the concentrations of these chemical compounds in meat products only made up a small portion of what global regulatory organizations consider safe for consumers.

“According to our exposure evaluation, it would be extremely difficult for a human to ingest enough fat from calves fed hempseed cake to go over legal limits for dietary THC exposure.”

David Smith with the Animal Metabolism-Agricultural Chemicals Research Unit in Fargo, North Dakota.

Hemp and products made from cannabis plants (Weed sativa L.) have been utilized for millennia for fiber, food (seeds and oil), and restorative purposes. Although the plant contains more than 80 naturally occurring cannabinoids, the two most well-known and biologically active are CBD and THC. In the modern era, plant breeders have cultivated cannabis plant varieties with relatively low CBD and THC concentrations for fiber and oil seed production (industrial hemp) and high CBD and THC concentrations for recreational and medicinal use.

The production of industrial hemp in the United States (U.S.) was made legal by the 2018 Farm Bill, which stipulated that industrial hemp must contain less than 0.3 percent THC in its dry matter. The low level of THC separates hemp items from pot or restorative weed assortments, which might contain more noteworthy than 5% THC.

Companies are now producing hemp seed oil from cultivars with very low THC content (less than 0.01%), as industrial hemp develops as an agricultural commodity in the United States. Hempseed cake, a significant byproduct of oil extraction from industrial hempseed, is difficult to sell for producers of hemp seed oil.

Hempseed cake is very healthy. In fact, a study that was carried out by NDSU in collaboration with USDA-ARS demonstrates that hempseed cake is a viable alternative source of cattle feed.

For 111 days, groups of heifers were fed either a control diet or a diet containing 20% hempseed cake in Smith’s study recently published in Food Additives & Contaminants. To find out how quickly cannabinoids are eliminated from tissues, cannabinoid residues were measured in the liver, kidney, skeletal muscle, and adipose tissue of animals harvested 0, 1, 4, and 8 days after hempseed cake was eliminated from the diet.

The hempseed cake that was used in the study had an average concentration of 1.3  0.8 mg/kg of both CBD and THC, which is 1/3000 of the legal limit of 0.3 percent (3000 mg/kg) THC.

During the feeding period, cannabinoid residues were occasionally found in the cattle’s urine and plasma. Adipose tissue (fat) from cattle harvested without a withdrawal period also contained low levels of CBD and THC (about 10 parts per billion). In liver, kidney, and skeletal muscle, notwithstanding, CBD and THC were below discernible levels in the dairy cattle that took care of hempseed cake.

“As per our openness evaluation, it would be extremely challenging for a human to consume sufficient fat from dairy cattle taken care of with hempseed cake to surpass administrative rules for dietary THC openness,” said David Smith with the Creature Digestion Horticultural Synthetics Exploration Unit in Fargo, North Dakota.

Smith continued, “From a food safety perspective, hempseed cake can be a suitable source of crude protein and fiber in cattle feed due to its low cannabinoid content while offering industrial hemp producers a potential market for this byproduct of hempseed oil extraction.”

The U.S. Food and Drug Administration is responsible for making the final decision and granting approval for the legal use of hemp products in animal feeds.

More information: David J. Smith et al, Excretion and residue depletion of cannabinoids in beef cattle fed hempseed cake for 111 days, Food Additives & Contaminants: Part A (2023). DOI: 10.1080/19440049.2023.2187645

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